1. Field of the Invention
The present invention relates to a water and oil repellant which satisfies drape and handle and practical durability of water and oil repellency simultaneously
2. Discussion of the Background
Heretofore, a technique treating fiber products, etc. with an organic solvent solution or an aqueous dispersion containing a perfluoroalkyl group-containing compound or a copolymer obtained by polymerizing polymerizable monomer containing a perfluoroalkyl group, to impart water and oil repellency to the surface of such materials, has been known. This water and oil repellency is attributable essentially to formation of a surface with a low surface energy on the materials due to the surfacial orientation of the perfluoroalkyl groups. In addition to such essential function, the water and oil repellant of this type is required to have additional properties such as flexibility and durability including washing resistance (hereinafter referred to simply as HL resistance), dry cleaning resistance (hereafter referred to simply as DC resistance) and abrasion resistance; flexibility and stain proofing properties; and stain proofing properties and SR properties (soil-removing properties). Particularly, for a water and oil repellant for fibers, it is highly desired to simultaneously satisfy the water and oil repellency as the essential function and the additional effects, particularly flexibility as the main additional effect. As a technique to satisfy such mutually opposing effects as the flexibility and the durability from the practical viewpoint, it has been common to employ (1) a method of improving the molecular structure of the treating agent and (2) a method of using an additional agent for the treatment. The method of improving the molecular structure of the treating agent includes a method of introducing an organopolysiloxane as a flexibility-imparting component, such as a method of employing a copolymer of a fluorine-containing (meth)acrylate with a siloxane-containing (meth)acrylate (Japanese Unexamined Patent Publication No. 190408/1975), a method of employing a reaction product of a fluorine-containing urethane compound with a reactive organopolysiloxane (Japanese Unexamined Patent Publication No. 81278/1975 or a method of using a perfluoropolyether as a side chain for a poly(meth)acrylate (Japanese Examined Patent Publication No. 6187/1976). However, a treating agent capable of providing flexibility tends to have low durability or low water and oil repellency. On the other hand, a treating agent having high durability tends to bring about poor drape and handle.
As an attempt to improve the durability, it is known to employ an additional agent for the treatment of fibers. As such a additional agent for the treatment of fibers, it is common to employ a melamine resin, a glyoxal resin or a urea resin. However, when such a resin is employed, there has been a drawback that the drape and handle tend to be poor. For the purpose of improving the flexibility, it has been proposed to use organosilicone in combination with a fluorine-containing treating agent or to apply it in a two step treatment (Japanese Unexamined Patent Publication No. 157380/1984). Although the durability may be at a satisfactory level, no practical solution has been obtained for the flexibility so long as a fluorine-containing polymer being a hard component is used as the treating agent. Further, a technique of blending a fluorine-containing polymer emulsion and a urethane compound emulsion in a latex stage, is also known particularly for treatment of fibers in an aqueous system (Japanese Unexamined Patent Publication No. 16454/1987). This technique teaches one direction for simultaneously satisfying flexibility and durability. However, in the case of simple blending of latexes, the dried coating film tends to be macroscopically non-uniform, whereby the durability (particularly the HL resistance and the abrasion resistance) tends to be low. Besides, blending different types of latexes is not easy, and it becomes very important to properly select the emulsifier to secure the stability.